Two other processes are also usually included with industrial emissions. The first is the production of cement, which releases large amounts of CO₂ as the limestone is prepared. The second item is gas flaring from oil fields. Above an oil deposit, there is nearly always a natural gas pocket. These are usually burned off as the gas reaches the surface and are not stored for use.

Fossil fuel burning can be thought of only as an input to the carbon cycle, since it takes millions of years for new fossil fuel reserves to be formed. Here is another way to think of this: It took millions of years to store the carbon in Earth's coal, oil and gas reserves, but humans will essentially deplete them in a span of 300 years.

In the U.S., utilities account for 36% of CO₂ emissions from fossil fuel burning. Transportation produces 31%, industry 22%, and the remaining 11% is residential and commercial heating.

Emissions can be broken down by fossil fuel type. Petroleum products account for 44%, coal 36%, and natural gas 20% of CO₂ emissions in the U.S.

Worldwide emissions of CO₂ from fossil fuel burning have stabilized in the 1990s at 6000 to 6200 million tons of carbon. This is dramatically higher than the 1638 million tons emitted in 1950, however. Worldwide emissions data can be found in the Fossil-fuel Burning activity, where the effect of fossil fuel burning on CO₂ levels in the atmosphere is investigated.

[ Greenhouse Gases: Greenhouse Effects /
CO2 History / Biomass Burning / Industrial Emissions ]
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